Many systems and semiconductor circuits employ a band gap reference voltage generator circuit as means for generating a direct current (DC) reference voltage that is appropriately stable to temperature. There have been many conventional attempts to reduce temperature dependency of the output and generate an accurate reference voltage independent of temperature.
A conventional band gap reference voltage generator circuit generates a reference voltage by summing two voltages whose temperature gradients are opposite and balanced to each other. In this case, one of the voltages is a base-emitter voltage Vbe (this is a base-emitter voltage of a bipolar transistor with a temperature coefficient of −2 mV/° C.) that is a forward voltage of a PN junction and that has a negative temperature characteristic. The other voltage is a voltage having a positive temperature characteristic of a forward voltage difference (ΔVbe) of the PN junctions.
For example, Patent Document 1 aims to provide a reference voltage generator circuit having both of a high temperature characteristic and a low temperature characteristic and whose temperature range in which improved voltage accuracy is obtained is expanded. The reference current generator circuit is provided for outputting a reference voltage based on a band gap. The reference voltage generator circuit includes a reference voltage output unit, which includes a PN junction device and a plurality of resistance elements and outputs a voltage obtained by correcting the band gap of the PN junction device with the resistance elements. In addition, the reference voltage generator circuit has a switch for changing a temperature characteristic of the output voltage of the reference voltage output unit, and a switch operation unit for operating the switch according to temperature.